replaced /bin/echo with printf, Solaris echo doesn't recognize -n

gitolite setup fails to check admin pubkey, because $text always
contains 2 or more lines after tsh_try() (the key and -n).

[committer adds:
    I wasn't sure if 'printf' would work on cygwin, so I chose what
    looked like a safer option, but apparently it wasn't safe enough and
    fell afoul of Solaris.

    Anyway I managed to check (using a small test program) with someone
    who runs gitolite on cygwin, and it works.

    If you're wondering why I didn't just use echo followed by chomp(),
    that would of course have been the easy way out but I wanted to see
    how you'd do it without a post-processing option.  It became a
    frustrating challenge of sorts because it seems such a trivial thing!
]

src/lib/Gitolite/Common.pm

@@ -277,7 +277,7 @@ sub logger_plus_stderr {
 
     sub tsh_try {
         my $cmd = shift; die "try: expects only one argument" if @_;
-        $text = `( $cmd ) 2>&1; /bin/echo -n RC=\$?`;
+        $text = `( $cmd ) 2>&1; printf RC=\$?`;
         if ( $text =~ s/RC=(\d+)$// ) {
             $rc = $1;
             trace( 3, $text );